Transformer coupled induction heater



April 30, 1935.

J. K. DELANO TRANSFORMER COUPLED INDUCTION HEATER Filed Oct. 6, 1935 2Sheets-Sheav 1 3nventor dam es K. .Delavm.

I Gttomeg April 30, 1935. J. K. DELANO TRANSFORMER COUPLED INDUCTIONHEATER- Filed Oct. 6, 1953 2 Sheets-Sheet 2 Enventor (James hi. Delano.

Patented Apr. 30, 1935 PATENT OFFICE TRANSFORMER COUPLED INDUCTIONHEATER James K. Delano, New York, N. Y.

Application October 6, 1933, Serial No. 692,380

8Claims.

This invention relates to an electrically operated heating device orunit for the heating of water and the generation of steam, or theheating of any other fluid, such as oil, etc., and in its broadapplication may be made to heat metals for use in various apparatuswhere a highly efficient heating effect is required.

The invention employs novel methods for carrying out the idea of directheating of the liquid, eliminating the use of insulation between theelectrical conductor and the liquid, thus greatly increasing thetransfer of heat and saving the losses which occur when packing andinsulation are present as used in the usual resistance types of heaters.

The method that I employ makes use of the heat generated in anelectrical winding which is shortcircuited within itself and subjectedto an alternating magnetic field.

For the purpose of description, I show in the drawings, a transformerwhich has the usual closed magnetic circuit, a primary winding'and asecondary winding composed of a copper pipe coil wound over the primaryand insulated there-' from and having the coils of the pipe connectedtogether so as to be entirely shortcircuited within the magnetic field.

As the pipe secondary is shortcircuited there will be no voltagegenerated which would be harmful in handling.

With the proper amount of cross section of copper in the secondary coilthe amperage will be high enough to cause the coils to heat, and bydesigning the primary winding, turns. ratio, etc., the proper magneticcircuit, the heater can be held to close limits of temperature.

By pumping or circulating liquid through the secondary copper pipe coilthe fluid will be heated very efficiently as-it is held during itscirculation directly in contact with the heated surface of the pipecoil. In the case of steam, the water is pumped into the pipe coil, andthe design of the coil is such as to permit a heating effect of over 212degrees, steam being generated. If a flash boiler effect is wanted toraise steam instantly, the secondary current can be increased until theturns or pipe coils are well above the boiling point of water, and bylimiting the amount of water entering the coils the steam can be raisedquickly toa superheated degree.

Thermostatic controls can readily be applied to the unit for controllingits operation.

Water can be heated very efiiciently for various purposes and thesecondary may consist of a single large capacity pipecoil, or it mayconion.

sist of numerous small turns or pipe coils for other applications anduses.

The primary is so designed that it will deliver to the secondary only amagnetic flux of limited capacity, else the current in the secondarymight 5 be high enough to cause the primary current to go too high,causing insulation difliculties.

This is accomplished by making the core of the transformer of such shapeand proportions that magnetic leakage tends to limit the current, 10 andit is also important to limit the cross section of the secondary pipecoil.

Other metals than copper, such as iron may be used for'the secondarypipe coil, which will, due to its resistance temperature coeflicient, bepractically self-regulating as to its heat and current, this beinguseful in a water heating storage system to cut the current down when acertain capacity of water has reached a given degree of temperature.

For high steam generation, a preheater pipe coil can be wound inside ofthe steam generating pipe coil, this preheater pipe coil can .be of thesame material or of a different resistance material than the main pipecoils, as it is in the magnetic field it receives current whichheats itindependent of the main pipe coil, the cold water being pumped into thisfirst pipe coil where it is heated and delivered to the. main pipe coil,where it is converted into steam, the inner or preheater pipe coil isshortcircuited where it enters and leaves the main pipe coil, and thismethod of preheating the cold water is very efiicient and steam can beraised from cold water in a boiler of this type in a few seconds, and Ihave shown this arrangement in one of the drawings.

In the drawings, I have shown a simple application of the principle asapplied to a water heating system and it is understood that variousheating arrangements could be arranged to take advantage of thisprinciple of heating as described, and that various regulators could bear anged to control the operations of the device.

With these and other objects in view my invention consists in certainconstruction and combination of parts as will hereafter be fullydescribed and claimed, and illustrated in the accompanying drawingswhich form a part hereof and in which like figures of reference refer tocorresponding parts in all of the views, and it is understood thatslight changes may be made without departing from the spirit of theinven- In the drawings: Figure 1 shows a front elevation of the devicewithout any outer casing or mounting means,

as these will vary with the use to which the device is applied and arenot important as regards its operation, and have therefore been omittedfrom the drawings.

Figure 2 shows a side elevation of the same.

Figure 3 shows a top plan view of the same.

Figure 4 is a diagrammatic view, showing the application of the deviceto a water heating system.

Figure 5 shows a front elevation of another form of the deviceillustrating the method employed for preheating the liquid.

Figure 6 is a top plan view of the same, both of these Figures 5 and 6,being shown partly in section.

Referring to the drawings:

The heater comprises as here shown, an electrical transformer composedof the core or laminations l0, upon which is mounted and insulatedtherefrom by the insulation strips Ii, the primary winding l2, which isconnected into the current supply by the wires l5, which supplyelectrical current of the propertype and voltage to said coil i2. 7

As shown in Figures 1, 2 and 3, the secondary comprises a coil formed bya pipe l3 which is coiled and mounted upon the primary winding I2 andinsulated therefrom by the packing I6, which is also employed to coverthe coils l3 and retain the heat therein.

This secondary coil I3 is employed to heat the liquid which is caused toflow therethrough, and the heating is effected by shortcircuiting thesecoils l3 by the strips ll which are attached thereto by brazing as at[1, or some other suitable means, and these strips I may also be usedfor the mounting of thermostatic controls.

The secondary pipe coil I3 being thus shortcircuited within the magneticfield will become very hot, and will cause the liquid passing therethrough to become heated to and above the boiling point if desired,depending upon the speed with which the liquid is forced through thecoil I3 and the design of the heater.

In Figure 4, the heater is shown as mounted in a hot water system, andattached by the flow pipe and return pipe to a water supply l8 having aflow pipe is and a return pipe 20, to the heating radiators, etc.

For the purpose of preheating the cold water or other liquid before itis brought into direct contact with the heated secondary pipe coil 13, Ihave shown in Figures 5 and 6, a transformer comprising the core l0,having a primary winding [2 mounted upon one leg thereof, and a mainsecondary hollow pipe coil l3 mounted upon the other leg of thetransformer [0, while mounted upon the same leg or some other part. ofthe transformer is a preheater coil 24 of a smaller diameter pipe 2|,through which the liquid is passed by the pump 22 or other means from afeed Pipe 23.

This preheater coil 24 is given a few turns about the transformer and isthen inserted into the upper coil of the main pipe coil I 3, and ismounted within said coils I3 for their entire length, its lower endbeing mounted in the plugged or closed end 21 of the coil I3, the end ofsaid pipe 2| being also closed upon the end, but provided with anopening 25 in its side adjacent the end, through which the preheatedliquid is admitted to the pipe coils I3, the direction of travel ofopposite to that of the steam within the pipe l3, so that in this mannerthe pipe 2| enters the hottest part of the coil l3 and the liquid iscarried through the steam heated coil l3 and by the time it is releasedtherein it has been converted into steam, thus producing a flash type ofelectrically heated boiler.

Various thermostatic controls can be employed in connection with theprimary circuit to turn on and oil, or regulate the current to produce agiven temperature in the secondary or heating element. Such thermostaticdevices may be of any of the well known types now in use and need not bedescribed in detail, as any one skilled in the art can readily applysuch controls to accomplish a desired result.

It is understood that this heater generates heat by the high amperagedeveloped in the low resistance secondary coils and it has been foundthat the efficiency is higher than in the resistance type of heater,when applied in its various forms for a specific purpose.

I have not attempted to give data as to the winding turns, iron, etc, asthese will vary with the uses to which the invention is to be put.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. In an electrically operated steam boiler, comprising an electricaltransformer having a laminated iron core designed to produce a closedmagnetic field, a primary winding thereon and insulated therefrom, ahollow secondary coil winding within said magnetic field and insulatedtherefrom and having a closed end, a shortcircuitin member connected tothe convolutions of said secondary coil to form a closed circuit withinitself, a second tubular coil mounted within said magnetic field andhaving a portion of its convolutions shortcircuited to form a localcircuit and having one of its ends wound spirally within theconvolutions of the secondary coil and formed with an opening near itsclosed end adjacent to the closed end of the secondary, and means foradmitting water through said second inner coil to the closed end of thesecondary coil.

2. In an electrically operated steam boiler, the combination with anelectrical transformer having a laminated iron core designed to producea closed magnetic field and a primary winding thereon and insulatedtherefrom, of a hollow secondary coil winding formed with one of itsends closed and mounted on said transformer and insulated therefrom, theconvolutions of which are shortcircuited to form local circuits, asecond tubular coil of smaller diameter mounted within the same magneticfield and having a portion of its convolutions shortcircuited to formlocal circuits, and a portion of its convolutions contained within theconvolutions of the secondary coll, said second coil having a closed endformed with an opening adjacent thereto and to the closed end of thesecondary coil.

the liquid being Cl 3. In an electrically operated steam boiler, the

combination with a transformer having a laminated iron core designed toproduce a magnetic field and a primary winding mounted in the magneticfield and having a portion of its convolutions shortcircuited and somemounted within the convolutions of the secondary coil, the

- inner end of said preheater coil closed and formed with an openingadjacent to and within the closed end of the secondary coil, means forpassing water through said preheater coil to preheat the same and todeliver the water in the form of steam to the closed end of thesecondary coil and means for preheating the steam thus generated withinthe secondary coil.

4. In a liquid heater, an electrical transformer having a laminated coreand a closed magnetic circuit and a primary winding connected directlyacross the current supply mains, a secondary tubular coil windingmounted on said transformer within the magnetic field, a shortcircuitingmeans connected to each of the convolutions of said secondary coilforming local circuits therein.

5. In a heater for liquids, an electrical transformer designed toproducea closedmagneticfield, a single primary winding thereon andconnected directly across the current supply mains, a hollow secondarycoil winding mounted on said transformer within the magnetic field andhaving each of its convolutions shortcircuited, and a hollow preheatercoil having a portion thereof mounted within saidhollow secondary coilfor the purpose of discharging the liquid therein at the closed end ofsaid secondary coil.

6. In a liquidheater, an electrical transiormer having a laminated ironcore designed to produce a closed magnetic field, a single primarywinding mounted on said core and-connected directly across the currentsupply mainaasecondarytubular coil winding mounted over said primarywindcoil winding mounted on said transiormerwithin the magnetic fieldand insulated both from the primary coil and the transformer core,shortcircuiting bars connecting each of the convolutions 01 saidsecondary coil to form local circuits within the magnetic field, andmeans for passing the liquid to be'he'ated through said secondary coil.

8. In a heater for liquids, an electrical transformer designed toproduce a closed magnetic field, a single primary winding thereon'andconnected directly across the current supply mains, a hollow secondarycoil mounted on said transiormer within the magnetic field and havingeach oi its convolutions shortcircuited to form local circuits, a closedend formed on said secondary coil, a hollow preheater coil having aportion thereof contained within the secondary coil with its dischargeend adjacent to the closed end of the secondary coil, said preheatercoil adapted to'be heated and the liquid passing therethrough by thesteam generated within the secondary coil and by the induced current dueto the shortcircuiting oi the preheater coils.

JAMES K. DELANO.

